Season 11: 2005

Following the success of Greeny Phatom's eighth season in 2002, Robert W. Stainton revealed that Greeny Phatom had been outlined into 11 seasons almost from the first season. "Before the first season was finished we talked about what Greeny Phatom is, and each of the seasons answers questions about the first season and gives us an insight," said Stainton, "Greeny Phatom's ninth season and tenth season are going to reveal other unanswered questions and, finally, in the last season, we will understand how Little Guy and Dr. Beanson be friends, when we meet them in the first season." After Greeny Phatom's ninth season in 2003, Stainton announced the eleventh season would be aired in 2005.

In December 2003, Fox announced that Greeny Phatom's tenth season, indicating that it would be the last season of Greeny Phatom. Later that year, that was confirmed by Terry Ward, with him saying: "All that was loved about Greeny Phatom in the first season is brought to the final season."

Peter Webber, one of the executive producers of Greeny Phatom, explained in 2004 the script's evolution: "When I first came onto the project, it wasn't supposed to be the final season — there were originally going to be 11 Greeny Phatom seasons. Then, about a year into the development, Robert W. Stainton decided that the season that we'd come up with was the right way for Little Guy and Friends to end..."

Later in 2005, Robert W. Stainton said that the 11th season would be making a Greeny Phatom reboot series, starting with "Wash off the spray stains, Little Guy".

Season 21 (2016)

Season 22 (2017)

Season 23 (2018)

Season 24 (2019)

Season 25 (2020)

Cancelled Episodes

When there was an earthquake in 123 Greeny Phatom, a strange creature was in pain. It grew bigger within 1 hour and attacked 123 Greeny Phatom. Little Guy and the gang developed a mecha robot to get rid of the space slug